Severe brain injury and trends of gestational-age-related neurodevelopmental outcomes in infants born very preterm: A population cohort study

Aim: To investigate the impact of severe neonatal brain injury (SNBI) on gestational age-related trends in neurodevelopmental impairment (NDI) outcome in infants born very preterm. Method: A population-based cohort study recruited 1091 infants born at a gestational age of less than 31 weeks between 2011 and 2020. The trends in neonatal morbidities, mortality, and 24-month NDI severity (no/mild, moderate, severe) by epoch (2011–2015, 2016–2020) and gestational age (22–25 weeks, 26–28 weeks, 29–30 weeks) were determined in infants with and without SNBI inclusion. Results: There was increased antenatal steroid use and higher maternal education and socioeconomic status over time. The rates of neonatal morbidities and mortality had no temporal changes. Among 825 infants with follow-up, those in the 22 to 25 weeks gestational age group had declining trends in cerebral palsy and severe cognitive impairment, with decreased rates of severe NDI from 19% to 8% across epochs, particularly in those without SNBI (from 16% to 2%). Relative to its occurrence in epoch 2011 to 2015, risk of severe NDI was significantly reduced in epoch 2016 to 2020 (adjusted relative risk 0.39, 95% confidence interval 0.16–0.96) for infants born at 22 to 25 weeks gestational age, and the risk dropped even lower in these infants without SNBI (0.12, 0.02–0.84). Interpretation: Infants born at 22 to 25 weeks gestational age had decreased rates of severe NDI in the decade between 2011 and 2020, particularly those without SNBI. The improvement might be attributed to better perinatal/neonatal and after-discharge care.